RET for optical maskless lithography

• US 20050219502A1
• Filed: 02/25/2005
• Published: 10/06/2005
• Est. Priority Date: 02/25/2004
• Status: Active Grant

• Current Assignee: Micronic Laser Systems AB (Mycronic AB)
• Original Assignee: Micronic Laser Systems AB (Mycronic AB)
• Inventors: Sandstrom, Torbjorn, Martinsson, Hans
• Granted Patent: US 7,618,751 B2
• Time in Patent Office: Days
• US Class Current: 355/77
• CPC Class Codes: G03F 1/26 Phase shift masks [PSM]; PSM blanks; Preparation thereof
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices

Abstract

The present invention relates to Optical Maskless Lithography (OML). In particular, it relates to providing OML with a recognizable relationship to mask and phase-shift mask techniques.

Claims

1. Method of exposing lithographic patterns, including:

providing a spatial light modulator (SLM) having at least one mirror having a complex reflection coefficient with a negative real part and an adjacent mirror having a complex reflection coefficient with a positive real part,

illuminating said SLM with a partially coherent beam,

converting vector input data to drive said SLM, said vector input data including more than two beam relaying states, as used in one or more of methods of lithographic image enhancement used with reticles, among the group of

CPL lithography,

phase edge lithography,

alternating aperture (Levinson type) lithography,

three-tone lithography, or

high-transmittance attenuating lithography.

2. The method of claim 1, wherein one or more pattern edges are defined by the SLM using at least one mirror oriented to have a complex reflection coefficient with a negative real part, emulating one or more of the methods of lithographic image enhancement.

3. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to a phase edge as contrasted with one or more adjacent mirrors; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

4. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to emulate phase interference between areas of a CPL mask; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

5. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to emulate an alternating aperture phase-shifting mask; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

6. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to emulate a three-tone phase-shifting mask; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

7. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to emulate a high transmission attenuating phase-shifting mask; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

8. Method for exposure of lithographic patterns, including:

providing a spatial light modulator (SLM) having at least one mirror having a complex reflection coefficient with a negative real part and an adjacent mirror having a complex reflection coefficient with a positive real part,

illuminating said SLM with a partially coherent beam,

converting vector input data to drive said SLM, said vector input data including OPC features or decompositions, as used to produce lithographic image enhancement used with reticles, among the group of

scatterbars,

serifs,

OPC jogs, or

double-dipole decompositions.

9. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to emulate one or more sub-printing resolution scatterbars; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

10. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to emulate one or more sub-printing resolution serifs; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

11. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to produce a jog in a line pattern, enhanced by a phase difference between adjacent mirrors of the SLM; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

12. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to emulate double-exposure dipole decomposition resolution enhancement using multiple exposures of the SLM; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

13. A method of direct writing to a workpiece, the method including:

receiving data that describes one or more masks applying phase shifting techniques to produce an image on the workpiece;

driving complex amplitude-capable micromirrors of an SLM to emulate the image on the workpiece that would be produced by the one or more masks; and

illuminating the SLM with partially coherent light and relaying the partially coherent light onto the workpiece.

14. The method of claim 13, wherein the one or more masks applying phase shifting techniques include two or more masks of a mask set used to produce an image on the workpiece for a particular pattern layer.